Heart murmur: what it is, types and associated diseases

A heart murmur refers to the presence of an additional, unusual sound heard during a heartbeat. It is described as hissing, screeching, or harsh.

So, although the majority of heart murmurs are harmless (especially if they appear in children), in some patients they may be a sign that there is a heart problem or other serious health problem under -lying. In these cases, treatment may be needed to keep the heart healthy.

The presence of heart murmurs is more common than you think, according to the latest studies heart murmurs affect up to 72% of children under 12 years old. Generally, this noise disappears over time. Although, in some cases, it can last well beyond adolescence. Additionally, certain pathological conditions, such as valve disease, are common causes of heart murmurs in adulthood. In this article we describe the two types of heart murmurs, their causes and how they occur.

    What is a Heart Murmur?

    The unusual sound caused by the passage of blood through heart valves this is called a heart murmur. This happens because the blood flow through the heart causes friction and turbulence in the vein. Most of the time, this has a harmless effect; however, in some cases it may be a sign of a more serious condition.

    This presence of an unusual sound is that of blood flows in an unusual way. It may, for example, happen through a defective heart valve. Or due to the presence of a condition that causes the heart to beat faster than normal, forcing it to handle more blood.

    A doctor who listens to our heartbeats using a stethoscope normally listens to the typical sounds of blood flowing through the valves of the heart. If the sound is unusual or irregular, it is called a heart murmur.

    A puff is, in a nutshell, a sign that healthcare professionals notice during cardiovascular examination. Healthcare professionals examine patients’ hearts through different physical examination techniques. Heart murmurs differ from normal heart sounds in their characteristics, for example, they may have a different duration, rhythm or pitch.

    During a cardiovascular exam, doctors look for signs such as sounds or murmurs. The main technique of physical examination is cardiac auscultation, which requires good hearing ability and can distinguish subtle differences in the pitch and duration of sounds.

    Hearing-impaired professionals can use stethoscopes with amplification. Another examination technique is palpation, which detects vibrations called “shivers” or heart palpitations through touch. These vibrations could be described as the feeling of friction that the hand perceives, comparable to the purring of a cat. Detection of heart murmurs still has pathological significance.

    As we have seen, the detection of these important indicators can indicate the presence of different valvular conditions or pathologies, such as heart disease, in patients. Likewise, heart murmurs they can be present at birth (congenital) or develop later in life (acquired).

    There are many types of murmurs and they are useful in determining signs of heart or vascular disease. Some heart murmurs are harmless; they are known as “innocent heart murmurs”. However, some murmurs indicate an underlying heart problem and should be further investigated by a specialist.


      The heart is divided into four chambers separated by valves which adjust the amount of blood that enters each chamber at the same time. The valves also help the heart to avoid backflow of blood; they close and open to allow blood to flow through the two upper chambers of the heart, called the atria, and the two lower chambers, called the ventricles.

      A healthy heart makes a sound called “lub-dub” as it contracts and relaxes, alternatively a person in poor health emits a buzz. The “lub” (systolic sound) occurs when heart muscle tissue contracts and the atrial valves (mitral and tricuspid) close. The “dub” (diastolic sound) occurs when the heart muscle tissue relaxes and the upper valves (aortic and pulmonary) close to prevent the return of blood. A heart murmur is the presence of an additional sound during the heartbeat, which is heard as a “hiss”.

      The murmur is usually caused by turbulent blood flow through an abnormal heart valve. Although, alternatively, it can be caused by a condition that causes the heart to beat faster and take in more blood.

        Classification of Heart Murmurs

        There is a series of 7 main characteristics to classify the puffs:

          1. Time: refer to whether it occurs during contraction (systole) or relaxation (diastole) of the heart muscle.
          1. Shape: Refers to the intensity pattern. It can be constant, increasing, decreasing, or between increasing and decreasing.
          1. Location: refers to the place of the murmur where it occurs with the greatest intensity (epicenter), for example the second right intercostal space.
          1. Radiation: Refers to where the hit spreads. Normally, sound travels in the direction of blood flow.
          1. Intensity: refers to the power (intensity) of the sound, the beats are measured according to the volume they give to the stethoscope. These are classified according to the Levine scale which ranges from 0 to 6.
          1. Tone: A whisper is described as a hissing, screeching, or harsh noise. Depending on the tone, this noise can be classified as high, medium, low (low)
          1. Quality or Timbre: refers to other particular characteristics that the breath can have and helps us to describe it, such as: soft or aspirating, blowing, resounding, musical…

        Types of Heart Murmurs

        If a heart murmur is heard during a medical examination, the only thing we know is that there is turbulence in the blood as it passes through the heart valves.

        A breath, as such, does not lead to the realization of any type of diagnosis, since it can occur for different reasons, these can be of a physiological nature, that is to say non-pathological, or be related to a medical problem. Heart murmurs are divided into two categories: innocent and abnormal.

        What is an innocent heart murmur?

        That’s called an innocent shot a heart murmur with no clinical or pathological implications for the patient; it is not related to any health problem. It can be congenital or manifest in adulthood and does not require any type of treatment.

        There are many situations in which the murmur occurs physiologically (not pathologically). Many healthy children have heart murmurs, and some pregnant women also develop murmurs during pregnancy because the heart has to pump more blood to nourish the fetus. Other conditions such as fever, anemia (lack of red blood cells), hyperthyroidism, or strenuous exercise can also be linked to murmur detection. The majority of innocent murmurs occur during contraction of the heart (systole), so they are called systolic heart murmurs.

        In general, these blows are considered harmless; they are not related to any other underlying medical condition or heart problem. Simply, they may be a sign of the existence of faster than usual blood flow in the heart valves. Ultimately, people with this type of harmless heart murmur do not need to make lifestyle changes or seek treatment.

          what is a abnormal heart murmur?

          In some cases, murmurs can be linked to pathological problems. The heart can suffer from age, unhealthy habits or other conditions that make it work more than usual, which can damage or overload the heart valves. The murmur in this case is a sign that the heart valves are damaged, usually narrowing or hardening. Additionally, some people may be born with a faulty heart valve, either a structural defect or the presence of some other abnormality. In these cases, there are different treatments depending on the severity and extent of the injury.

          The most common valve problems are:

          • Mitral valve prolapse
          • Mitral or aortic valve stenosis
          • Aortic sclerosis and stenosis
          • Mitral or aortic regurgitation
          • Congenital heart defects

          Finally, heart murmurs are often not accompanied by any other signs and are discovered only during a physical examination. When symptoms appear (usually difficulty breathing or dizziness), they usually indicate the existence of an underlying condition, which includes damage to the valves.

          Bibliographic references

          • Doshi, AR (2018). Innocent heart murmur.
          • Thomas, SL, et al. (2021). Physiology, cardiovascular murmurs.

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